The goals of study are: i) evaluate pharmacokinetics of HBIg in liver transplants receiving this therapy as long-term prophylaxis for recurrence of HBV surface antigemia; ii) examine concurrent changes in titer of HBsAg and anti-HBs during HBIg therapy; iii) determine whether pts on HBIg who are HBsAg negative have residual HBV infection in serum liver or lymphocytes; iv) determine whether immune complexes can be identified and quantitated; v) determine whether HBV escape mutants are responsible for overt reinfection.